"As a consequence of these wartime spending choices, the United States will face constraints in funding investments in personnel and diplomacy, research and development and new military initiatives," the study report states. “The legacy of decisions taken during the Iraq and Afghanistan wars will dominate future federal budgets for decades to come."

The research revealed that the largest ongoing expense will be related to providing medical care and disability benefits to veterans, which have increased dramatically since 2001 and will continue to increase over the next 40 years.

Other significant costs include replacing equipment and the ongoing diplomatic and military presence in the region.

Linda Bilmes, the report's author, told the Washington Post that the U.S. has spent $2 trillion so far, a fraction of the ultimate price. However, the report points out, the bill for most conflicts usually comes decades later.

"Payments to Vietnam and first Gulf War veterans are still climbing," Bilmes noted.